Perhaps you should try some spelling variations:
thanh truong » thanh trung, thanh thuong, thanh tung
hieu quang » thieu quang, hieu quan, hieu qua
hieu sang » chieu sang, hieu lang, nhieu tang
truong va » truong dai, truong cao, truong dao
nang cong » dang cong, bang cong, hang cong
dan than » dan chan, ban than, van than
than cau » toan cau, phan cau, than cap

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu sang) or (hieu quang)) - thanh truong va ((nang cong) OR (nang song)) dan than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu quang)) - thanh truong va ((nang cong) OR (nang song)) dan than cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) or (hieu quang)) - thanh truong va ((nang cong) OR (nang song)) dan than cau".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) or (hieu quang)) - thanh truong va ((nang cong) OR (nang song)) dan than cau*.